The present invention relates to an improved appliance for use in conjunction with dental instruments to illuminate the oral cavity during the performance of dental work. The invention particularly relates to the design and use of an illumination system which enables quick separation of the fiber optic portion of the illuminator for cold liquid sterilization while enabling the dental instrument to be sterilized in a conventional fashion.
The use of fiber optic illumination in conjunction with dental treatment is well known. One of the prime objectives in providing illumination to the oral cavity is the elimination eye fatigue. An assistant can also independently direct a light source if desired Examples include U.S Pat. No. 3,614,415 to Edelman, entitled "Fiber Illuminator", U.S. Pat. No. 4,992,047 to Warner, entitled "Surgical Suction Tool", U.S. Pat. No 4,986,622 to Martinez, entitled "Fiber Optic Light Transmission Apparatus", and U.S. Pat. No. 4,704,660, to Robbins, entitled "High-Intensity Light Source for a Fiber Optics Illumination System."
Another system for fiber optic illumination is a clip on system made by Quality Aspirators of Duncanville, Tex. The scheme employed there includes a clip-on wand having an illuminating end opposite a compound curved connector end. The curve is for the purpose of mounting along the upward end of the dental instrument while allowing the fiber optic connector and its lead in cable to hang below the dental instrument.
This is an example of known schemes which involve the use of a number of glass fibers to transmit light from a light generator to a point proximate to a dental instrument. The light is further propagated and coupled into a rigid encased light guide within a cavity provided in a dental instrument. Typically the optic fiber bundle or fiber is epoxied or otherwise permanently encased or "potted" into a tube which is attachably held in place with respect to the dental instrument by solder or clips.
The point of connection between the rigid, encased light guide and the flexible fiber optic fiber or bundle always involves some difficulty. If the impedance match of the connection is not sufficiently good, significant amounts of light will be reflected from the point of connection back to the light source. This will cause a more intense light source to be required in order to deliver the same level of light to the illuminated area given the percentage reflection. Further, the excess light reflectively propagating in the volume between the flexible fiber optic bundle and the rigid encased guide representing a loss, will be converted to heat, potentially making the instrument uncomfortable to use.
The tube encasing the rigid light guide is closed at one end with a transparent cap or lens to couple and adjust light from the rigid light guide into the area to be illuminated. The sealing of the end of conventional fiber optic illuminators is important for several reasons. First, non-sterile liquids, such as saliva and blood could be wicked into the area between the rigid light guide and the tube encasing it by capillary action. This is particularly true where the rigid light guide is a fiber optic bundle, and additional wicking may occur between the fibers in the bundle.
Secondly, exposing the rigid light guide optical fibers directly into the oral cavity would cause their light transmissive properties to degrade due to the scoring to which the ends of the fiber would be subjected over time. However, the sealing of the end of the tube, and the fixing of the rigid light guide within the tube causes problems associated with sterilization. Once the dental instrument, including the tube encasing the rigid optical fibers has been used in the dental environment, it becomes necessary to sterilize the contaminated portions.
Since the fiber optic light guide is permanently encased within its supporting tube they must be sterilized together. High temperatures cause epoxy to break down and turn yellow in a short time period. A rigorous sterilization involving strong chemicals and high temperature for the instrument is also a rigorous sterilization for the encased rigid light guide. Exposure of the end of the tube connected to the flexible optical fiber to chemicals tends to harm the optical fibers, reducing the ability of the flexible fibers to transmit light into the rigid light guide. Further, exposure to other sterilization techniques causes degradation of the epoxy which holds the rigid light guide in place.
Further, repeated exposure of the rigid light guide optical fiber to high temperatures causes reduction of its light transmission characteristics throughout its volume. Light transmitted into the flexible optical fiber is energy, and any light not reaching the oral cavity for illumination there is expended elsewhere in the form of heat if not allowed to escape in the form of light. As the rigid light guide's ability to transmit light decreases, it absorbs light causing it to heat up. The heat is transmitted into the tube encasing the fiber and causes the tube and the dental instrument to become uncomfortably hot. As the light energy is absorbed in the instrument, the illumination level in the oral cavity becomes insufficient.
Further, the cost of manufacture of the conventional dental illumination system outlined above is expensive, both in terms of the rigid light guide within the dental instrument, as well as in terms of the flexible light guide used for transmitting light to the dental instrument, and especially the connector used to join the two light guides.
Illumination of the oral cavity can be accomplished by the use of fiber optics. However, what is needed is a system which will allow such illumination to take place inexpensively, which will not present an impediment to sterilization, either from reluctance to perform a full sterilization of the dental instruments in contact with the oral cavity to prevent harm to the fiber optic portions, or from a design not inhibitive of a full sterilization.
Further, a system is needed which will operate with as few points of loss as possible. The needed system should also be as efficient as possible, such that adequate light may be supplied with a low cost in terms of energy into the system. The geometry of such a low cost, efficient system should ensure complete sterilization, and enable adequate visual inspection of all areas where unsanitary contamination might exist.